DEPENDENCE OF ENERGY DISTRIBUTION IN THE KEYHOLE ON OPTICAL PARAMETERS OF THE FOCUSING SYSTEM IN LASER WELDING

摘要

Deep penetration laser welding performed by continuous high-power laser beam is characteristic by creation of a thin capillary, called a keyhole, within the welded material and the depth of the keyhole determines the depth of the resulting weld. Geometry of the keyhole and energy distribution on its walls depend mainly on the material properties and the welding parameters such as power, translation velocity and focus characteristics of the incident laser beam. This paper presents a physical concept and a numerical simulation of the keyhole creation and its inner energy distribution in dependence on geometric parameters of the laser beam which are given by focusing system of the welding machine. We show the impact of the size of a beam waist, its position with respect to the surface of welded material and total angular spread of focused beam on the keyhole depth and on the distribution of its walls irradiation. The results of numerical simulation are also compared to the depth of real material joint observed in material samples from testing welds.